This invention relates to a photoelectroporetic imaging method and, more particularly, to a method wherein an image is enhanced by subjecting the image to an applied electrical field in the absence of illumination.
In the photoelectrophoretic imaging method a layer of an imaging suspension comprising electrically photosensitive pigment particles in a carrier liquid is typically disposed between a pair of electrodes, at least one of which is at least partially transparent, exposed to an imagewise pattern of activating electromagnetic radiation and subjected to an electrical field established between the electrodes with the result that complementary images are formed on the surfaces of the respective electrodes.
Many embodiments of photoelectrophoretic imaging are known in the art. U.S. Pat. No. 3,553,093 discloses a polychromatic photoelectrophoretic imaging method wherein a layer of imaging suspension is arranged between a pair of electrodes, exposed to imagewise activating radiation and subjected to an electrical field to form an image on at least one of the electrodes. Subsequently, the other electrode is removed, either cleaned or replaced with another electrode and the imagewise exposure and electrical field application are repeated at least one additional time to improve the quality of the final image.
The present invention relates to a method for enhancing the degree of color separation and minimum density in polychromatic photoelectrophoretic imaging and for enhancing the minimum density characteristics for monochromatic images made by photoelectrophoretic imaging.